The present invention relates in general to electronic micrometers and, in particular, to a new and useful length measuring system which sends, as a test signal, two offset sinusoidal voltages whose curve depends on the longitudinal movement of the measuring system, to an interpolation circuit which sends to an evaluating circuit two high resolution rectangular pulse sequences corresponding to the interpolation sinusoidal voltages and which are offset by 90.degree..
Length measuring devices whose resolution is to be higher than the distance between marks on the scale of a measuring system, must operate with a correspondingly high interpolation factor. A high interpolation factor, however, presupposes that the two test signals are phase-locked relatively to each other and have constant amplitudes and D.C. voltage components.
On the other hand, length measuring devices should be brought to their test position at a high speed of travel. Due to the occurring accelerations, tilting or other interferences are then inevitable. As a result, the mentioned conditions for a high interpolation factor are not fulfilled. The length measuring device will then miscount.